From: François Cartegnie <fcvlcdev@free.fr>
Date: Mon, 13 May 2024 11:37:27 +0000
Subject: avcodec/decode: clean-up if get_hw_frames_parameters fails

https://trac.ffmpeg.org/ticket/11013
https://code.videolan.org/videolan/vlc/-/issues/28811

Fixes the following assert:

[00007f1df83d17e0] vaapi generic error: avcodec_get_hw_frames_parameters failed: -22
Assertion p_dst->hwaccel_threadsafe || (!dst->hwaccel && !dst->internal->hwaccel_priv_data) failed at libavcodec/pthread_frame.c:349

Reproduced from VLC with VAAPI, when fallbacking from hw to sw.

--- a/libavcodec/pthread_frame.c
+++ b/libavcodec/pthread_frame.c
@@ -344,6 +344,10 @@ FF_ENABLE_DEPRECATION_WARNINGS
                 return err;
         }
 
+       // hwaccel could have failed init due to some params
+       if(!dst->hwaccel && dst->internal->hwaccel_priv_data)
+           ff_hwaccel_uninit(dst);
+
         // reset dst hwaccel state if needed
         av_assert0(p_dst->hwaccel_threadsafe ||
                    (!dst->hwaccel && !dst->internal->hwaccel_priv_data));